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rectus internus, the ganoidean arrangement would arise; while if it 

 should traverse the nerve anterior to the point of origin of that branch 

 it would give rise to the teleostean arrangement. And either process 

 reversed would of course give rise to the arrangement found in Poly- 

 pterus. A comparison of my diagrammatic figure of the innervation 

 of the muscles in Amia and. Herrick's of that in Menidia will make 

 this plain; the arrangement in Polypterus being represented by a 

 diagram exactly similar to that of Amia but with the rectus inferior 

 ventral to the oculomotorius instead of dorsal to it. 



Impressed by the fact that Ameiurus alone of the Teleosts, so far 

 as known, should present a ganoidean arrangement in the innervation 

 of its eye muscles, I have been led to control Workman's statement 

 regarding this fish, examining for this purpose the nerves and muscles 

 on both sides of the head in two small larvae of Ameiurus. On the 

 right hand side (in the sections) of one of the two larvae, I find the 

 innervation as given by Workman, excepting in that there is but one 

 branch evident going to the rectus inferior. On the same side of the 

 other specimen there are two branches sent to the rectus internus, 

 and, after uniting, they perforate the rectus inferior quite close to its 

 ventral edge. On the left hand side of both larvae there are also two 

 branches sent to the rectus internus, but one of these branches, in 

 both cases, passes dorsal to the rectus inferior, while the other arises 

 from the oculomotorius after that nerve has passed ventral to the 

 rectus inferior; that is, the two branches lie one actually dorsal and 

 the other morphologically ventral to the rectus inferior. If the first 

 one of these two branches were to be suppressed, it would give rise 

 to the arrangement found in Amia, while if the second one were to be 

 suppressed the arrangement would be as in Teleosts. 



Ameiurus thus presents, in the manner of innervation of its eye 

 muscles, an arrangement that might be considered as intermediate 

 between the two quite different arrangements presented by Ganoids 

 and Teleosts. In the adult Amia (Allis, '97) the branches of the oculo- 

 motorius that are sent to each of the eye muscles innervated by that 

 nerve are all double, the two branches sent to the rectus internus 

 even arising from the main nerve at some little distance apart and 

 each being itself double. If this double condition of the nerve is also 

 found in larvae, it is evident that if the rectus inferior were to ac- 

 quire the teleostean relations to the nerves by a gradual shifting of 

 its point of origin relatively forward, anterior to the nerve that innerv- 

 ates the rectus internus, it would necessarily traverse first one nerve 

 branch to that muscle and then the other: thus giving rise successively 



